Q3 Super Multi Box – DC Combiner with Patent-Pending Fault Discrimination Technology
2025 . 05 . 15
DC Combiner for Large-Scale PV Systems: Smart Fault Discrimination for Utility-Scale PV – A New Benchmark in DC Combiners
The increasing capacity of ground-mounted photovoltaic systems presents ever more complex challenges for operators and service teams. Especially in systems with central inverters, a single faulty string can lead to the shutdown of an entire megawatt-scale section of the plant. This not only results in yield losses but also high service costs due to time-consuming fault diagnosis.
Q3 ENERGIE GmbH & Co. KG has developed a practical solution: the new Q3 Super Multi Box, a DC combiner featuring a patent-pending fault discrimination technology.
Inside the Q3 Super Multi Box: integrates smart fault logic, safety, and flexibility – ready to meet the demands of modern utility-scale PV plants.
One Box – Many Functions
The Q3 Super Multi Box is an advanced generator connection unit for large-scale PV systems using central inverters. Housed in an IP66-rated steel enclosure, it combines a range of safety and communication features:
⚙️ Individual string current monitoring for up to 24 inputs
⚙️ Electronic DC disconnection up to 480 A at 1,500 V DC
⚙️ Integrated PV fault manager with remote maintenance capability
⚙️ SPD Type 1+2 with remote signaling contact
⚙️ Fuses on the positive and optionally the negative pole (32 A / 1,500 V DC)
⚙️ Communication interfaces: Modbus TCP/IP, RS485, Ethernet or USB
⚙️ MC4-EVO2 input connectors and copper busbar output
The electronics are powered directly via the PV strings using a DC/DC converter. At night, the system remains communication-capable thanks to battery buffering.
Innovation: The "PV String Fault Discriminator"
The DC combiner incorporates a patent-pending technology for selective fault detection at string level. When a fault occurs (e.g. insulation fault or arc fault), all strings within the box are initially shut down. Then, an automated process reactivates each string one by one until the faulty string is clearly identified. The affected string is permanently isolated, while all others resume operation. System availability is maintained, and service intervention can be precisely planned.
A single faulty string shutting down a whole system section? That’s a thing of the past. With the Q3 Super Multi Box, we introduce a solution that truly relieves PV operators:
Gone are the days of multi-day yield losses and manual fault searches in the field, which used to be common for large-scale plants. The “PV String Fault Discriminator” marks a paradigm shift in utility-scale PV maintenance.
Practical Benefits for Operators and Service Providers
The benefits of the Q3 Super Multi Box are particularly evident in operation:
⚙️ Yield protection: only the faulty string is isolated
⚙️ Faster maintenance: automated fault localization
⚙️ High compatibility: connects to SCADA systems or inverters
⚙️ Modular design: adaptable to project-specific requirements
“Insulation faults are not uncommon in ground-mounted systems. The new Q3 technology saves us days of troubleshooting – and that’s real money saved!”
– Visitor at the Q3 booth at Intersolar 2025.
Developed from Real-World Practice
Q3 ENERGIE GmbH & Co. KG has been developing technical safety solutions for PV systems for over 15 years. Q3 ENERGIE is one of Germany’s leading technology companies in the field of firefighter switches. The Q3 Super Multi Box was developed in direct response to customer demands: to prevent single string faults from shutting down entire solar parks.
Building on the proven QFire technology, an automated individual string shutdown system was developed and enhanced with smart communication. The prototype was completed in under one year and unveiled just in time for Intersolar 2025. The underlying technology was filed for patent protection in May 2025.
Market Launch and Outlook
The Q3 Super Multi Box will enter serial production in Q3 2025. Project-based planning and quoting is available immediately. As Q3 manufactures to order, lead times of several weeks should be expected – a manageable factor for large-scale projects.
Looking ahead, Q3 plans to work closely with central inverter manufacturers to ensure early-stage compatibility and operational reliability.
Conclusion:
The Q3 Super Multi Box is more than just a combiner box. It is an intelligent building block for securing the operation of utility-scale PV power plants. With its new fault discrimination technology, it sets a new standard for efficiency, availability, and safety.
Author: Thomas Neumann, Managing Partner, Q3 ENERGIE GmbH & Co. KG
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